Set inventory moves readonly for picked customer shipment

Closes #12613
(grafted from e5736b1058c49e0789188d1171cb6fa9506a2143)

--HG--
branch : 6.0

modules/stock/shipment.py

@@ -1011,7 +1011,8 @@ class ShipmentOut(ShipmentAssignMixin, Workflow, ModelSQL, ModelView):
                 ],
             states={
                 'readonly': Eval('state').in_(
-                    ['draft', 'assigned', 'packed', 'done', 'cancelled']),
+                    ['draft', 'assigned', 'picked', 'packed', 'done',
+                     'cancelled']),
                 'invisible': (
                     Eval('warehouse_storage') == Eval('warehouse_output')),
                 },